Drying apparatus



S. H. MEIHUIZEN! DRYING APPARATUS.

APPLICATION FILED MAR.9, 191s.

Patented June 22, 1920.

2 SHEETS-SHEET l.

S. H. MEIHUIZEN.

DRYING APPARATUS.

APPLICAT-ION' mm MAR. 9. 1918.

Patented J um 22, 1920.

2 SHEETS-SHEET 2- [nuenlor gt J6 H01 0 MeiAu/ZLH,

UNITED STATES PATENT OFFICE.

SIJTSE HERO MEIHUIZEN, 0F VEENDAM, NETHERLANDS.

DRYING APPARATUS.

Application filed March 9,

To all whom it may concern:

Be it known that I, SIJTsE HERO MEI; HUIZEN, a subject of the Kingdom ofthe Netherlands, residing at Veendam, Nether lands, Oosterdiep B 35,have invented a new and useful Improvement in or. Relating to DryingApparatus, of which the following is a specification.

This invention relates to a drying apparatus, to be employed for dryingamylum or other materials, for instance for the purpose of determiningthe amount or quantity of water which they contain. There are dryingapparatus known, by which the drying-chamber is provided with a doublewall forming a acket in which aliquid is maintained at boiling point, sothat the temperature in the drying-chamber is established in accordancewith the boiling point of the. liquid. Should a different temperature berequired, another liquid'ean-be'employed or the pressure exerted on theboiling liquid may be varied, (see Dr. A. Stahlers Hand- Zmc/z, cierArbcz'tsmcthodcn in dew amorg.

Chem 5c 1915, page 472).

It has already been proposed to draw air, which may or may not all bepreviously dried and heated, through the drying-chamber, and to conveysaid air by means of natural draft through the drying-chamber to thechimney (Dr. C. Fresenius, Anlcz'tmzg 2w Qmmt. Chem. Analyse, 1905, vol.1, page 56).

Moreover it is known to introduce the material to be dried into thedrying-chamber by means of a framework, avl ich can be brought down inthe drying-chamber (see German patent No. 55,060). I

The apparatus, according to the present invention, consists of two tubesplaced one within the other. The inner'tube, forming the realdrying-chamber, is extended'so as to form a chimney, through which thedry air can be drawnfrom any suitable point by natural draft, and inwhich at the same time the framework with the materials to be dried canbe brought down. The second tube, in which is the boiling liquid, isalso extended at its upper end, so that the upper part of the space,formed between both of the said tubes, can be employed as acoolingchamber for the ascending vapor.

WVith the extension of the inner tube acting as a chimney above thedrying-chamber, the very important advantage is attained, that a goodair-circulation is effected by natural draft, no cover is needed andmore- Specification of Letters Patent.

surface of the materials to be dried.

Patented June 22, 1920.

1918. Serial No. 221,363.

over the framework with the weighing-cups can easily be introduced intoand removed from the apparatus.

Further, the present invention relates also to a construction forobtaining. a good circulation of the combustion gases from the source ofheat necessary for keeping the j acket-liquid boiling. This constructionconsists in the arrangement of a third tube, surrounding the second tubecontaining the water or other liquid and extending as far as thecooling-chamber to allow the combus tion gases from the source of heat,placed underneath the second tube, to ascend by natural draft throughthe space thus formed.

To prevent the vapor ascending too rapidly in the cooling chamber, 2'.c. to insure that no vapor passes the cooling-chamber uncondensed, thelatter can be filled up with a packing material, as for instance smallpebble-stones.

very important improvement as regards drying is obtained, according tothis invention, by forcing the air to pass along the For this purpose acomplete disk or plate of small size, is placed immediately under eachof the weighingscups stacked one above the,

other, a small space bein' between the bottom of each cup and itsrespective disk, as shown in Figure 1, which spaces may be formed by theprovision of upwardly extending projections or knobs on the disks. Thediameter of these small plates is less than the diameter of the dryingchamber. Above each of the weighingcups a second plate is arranged,provided in the middle'with one or more openings and fitting close tothe wall of the dryingchamber, so that the hot air is forced to passalong the surface of the material contained in the cups, Thisarrangement, for instance, when drying amylum, prevents the amylumpasting together and insures the removal or withdrawal of the water in amost complete manner.

Similar reference characters refer to similar parts in each of theseveral views.

In the accompanying drawings, Fig. 1 is a View showing diagrammaticallyone form of drying apparatus embodying my invention. 7

Fig.2 is a vertical sectional view on an enlarged scale, of the valveshown at the lower left side of Fig. 1, the valve casing beingillustrated diagrammatically;

preferably left Figs. 3 and 1 are respectively a side and an end view ofa clamping pincer adapted for use on the rubber tubes, a fragment oftube being shown in both of the views; and,

Fig. 5 is a fragmentary sectional elevation 01 the lower part of thedrying chamber, on an enlarged scale.

The drying-chamber is formed by the lower part of a tube 1, closed atthe lower end, and this tube is placed inside a second tube 2, likewiseclosed at its lower end. Through the wall of the tube 1 close to thebottom passes a tube 3, which also passes through the wall of the tube2, being hermetically connected to both tubes. To the outside of thewall of the tube 2 a pipe 4: is connected in alinement with the tube 3.This pipe is connected to a vertical tube 5, which at its upper end canbe closed by a plug 6, while the lower end of the tube is connectedthrough a mercury seal to one side 01? a receiver 7 containingconcentrated sulfuric acid. At the upper side of the other end of thereceiver 7 is connected a tube 8, which as shown in Fig. 2 is formedwith a valve casing 8 in which is located a valve 19. The valve 49consists of a paper disk which in its normal position is supported uponthe skeleton frame a supported upon a cork ring I). Arranged above thevalve 49 is another cork ring I) which, as shown in Fig. 2, limits theupward movement of the valve. By this arrangement, it will be seen thatwhen the valve is in the raised position, as shown in Fig. 2, the tube 8is disconnected from atmosphere. The tube 8 can be closed by means ofthe plug 6 when the latter has been removed from the tube 5.

The tube 2, which is provided with a drain-pipe at its lower end and ispartly filled with water, is surrounded by a tubular sheathing 9. Thissheathing 9 is closed at bottom by an asbestos card or plate 11,. havinga hole in the middle under which a spirit-lamp or the like may beplaced. This plate rests upon the upper end of a support 10 and bearsagainst the tube 9 as shown in Fig. 1. The space between the tubes 2 and9, which at the upper side is open, serves as a chimney for thecombustion gases of the lamp.

The reason why the asbestos plate is provided with a hole is to preventtoo much cold air ascending and also to enable an intimate mixing of thecombustion gases with the air to take place, in order to obtain completecombustion.

The part of the space between the tubes 1 and 2, in which thespirit-lamp causes the water to boil, situated above the chimney 9, ismade into a cooling-chamber (air-cooler). Furthemore, this part of thejacket may be filled up with packing material 12, for instancepebble-stones, in orderto assist the condensation of the liquid vapor.The

jacket-space is closed at the upper end 13, and is there connected witha pipe 14. This pipe 14, which is provided with three branches, havingthe form of small bends 15, 16, and 17, ends in a downwardly directedbend 18. The small bend 15 is, by means of a rubber tube 19 and a glasstube 20 connected to an air receiver 21 (for example a glass bottle).The bend 16 is in a similar way, by means of a rubber tube 22, a glasstube 23 and another rubber tube 24: connected to an open mercurypressure gage 25, for the constitution of which a Voulfhbottle isillustrated. At the small bend 17 a longer rubber tube 26 is attached towhich a glass tube 27 is connected. The bent extremity of the pipe 14:is also by means of a rubber tube 28 connected to a long glass tube 29.The latter has a lower beveled end resting on the bottom of a glasscylinder 30, which is partly filled up with mercury. On the rubber tubes19, 22, 26 and 28 screw pincers indicated diagrammatically at 31, 32, 33and 3 1 are arranged, to allow the rubber tubes to be pinched. tightly.The detail construction of the screw pincers is shown in Figs. 3 and 4.This is a common form of pincers and a detail description of the same isthought to be unnecessary.

To force the air, which enters through the tube 3 into thedrying-chamber formed by the tube 1, to pass along the heated wall ofthe latter in order to attain a good heating of this air, a completelyclosed tank 35, of which the diameter is only a little smaller than thediameter of the tube 1 is brought down as far as the upper side of thetube 3. An enlarged. detail view of the tank 35 and adjacent parts areshown in Fig. 5. As will be seen in Fig. 5, the tank 35 is supported bythe tube 3 and is secured thereto at 35. Above this tank a framework 36,suspended on a rope 38 running over two pulleys 37 and loaded with acounterweight 38, is placed in the tube 1, so that the framework can bemoved up and down in the tube 1.

In the framework 36 the weighing-cups 39 are stored one above the other,each of them being placed on a solid disk or small plate 41-0 having adiameter somewhat less than the diameter of the drying-chamber and fixedin the framework. These plates 40 may be provided with upwardlyprojecting parts or knobs, on which the cups may rest'. Above eachweighing-cup also another small plate 11 is arranged, which fits tightlyagainst the wall of the drying-chamber and has a hole just above thematerial contained in the weighing-cups. A similar solid disk or smallplate like the small plates 40 is fixed on the upper side of theframework, and provided with a hook, on which the framework is hung.Through this arrangement the weighing-cups are protected at the underside as far as possible against the hot gases,

and the air is only allowed to pass above the material to be dried. Whenpassing over the material the hot air absorbs vapor and is cooled. Thedrying is accelerated through the air passing over the material to bedried, which at the same time prevents any co1nmencement of pastingtogether of the amylum. 3

On the drawing an apparatus is illus trated such as is employed foroperating by a temperature somewhat above 100 degrees C. (for example105 degrees), as is most usual hitherto.

The mercury receiver 30 is filled up with mercury to a height of 17 cm.(about 6% inch). The screw pincers 31, 32 and 34 are loosened, whereasthe screw pincer 33 is screwed up. A moderate iiame is placed underneaththe apparatus. The water in the tube 2 rapidly commences to boil andvapor arises. This vapor removes the air in the space between the tubes1 and 2, said air being compressed in the air-receiver 21, the pipe 14and the Voulff-bottle 25. The mercury in the pressure gage ascendsslowly and stops at a certain height, corresponding with the height ofthe mercury column in the receiver 30. No further increase of thepressure can then take place, because the air would escape by ascendingthrough the mercury in the receiver 30.

After the air beneath the cooling-chamber in the space between the tubes1 and 2 is entirely removed, z. 6., as soon as this space is entirelyfilled up with vapor, the latter gradually condenses more and-more inthe cooling-chamber filled with pebble stones 12; consequently the airwill not be compressed further, and finally a state of equilibrium willarise, by which the pressure remains constant, and the vapor which isstill to be generated, is continually condensed= It is evident that caremust be taken that the cooling is so efficient that the generation ofvapor does not proceed more quickly than the condensation, which can beeasily attained with a suliicient cooling surface, and by preventing thevapor ascending too quickly (by means of the pebble stones) and by asufliciently moderate heating (a small flame). Since the pressure aboveatmospheric thus remains constant (17 cm. mercury pressure), thetemperature will remain constant in correspondence herewith andestablished at 105 degrees Celsius.

As shown on the drawing, the tube 1 is comparatively high, so that inthis tube, after it has become hot, sufficient natural draft isproduced, to provide automatic draft for the air which ascends into thedrying-chamber.

The air can as a preliminary be dried or not, but if dried in advance itis passed over the surface of concentrated sulfuric acid contained inthe receiver 7. In case such preliminary drying is required, the tube 5,

as shown on the drawing, is closed by the plug 6 and the air is drawnthrough the open tube 8. If it is desired to operate without preliminarydrying, then the plug 6 is simply put on the tube 8 and the air is drawnin such a case through the open tube 5. As represented on the drawing,the air receiver 21 is suspended near the drying apparatus for thepurpose of keeping the temperature of said receiver so high, that theair forced therein, is not cooled at all or at least very little toavoid too great a decrease in pressure.

For operating at a temperature of 100 degrees C. (atmospheric pressure)for in stance, the glass tube 29 is removed and replaced by a glass tubewhich is somewhat shorter and only extends to theupper surface of thecylinder 30. For the rest the operation proceeds in the same way as doscribed herein. It can be obtained in a more simple way by opening thescrew pincer 33, or uncoupling the tube 14.

Should it be required to operate at a temperature lower than 100 degrees0., for example 65 degrees C., then the glass tube 27 is brought intoconnection with a suction pump after the screw pincer 33 is opened, (thescrew pincers 31 and 34 were already open). Now the air is sucked bymeans of the pump out of the apparatus, and consequently out of theair-receiver 21, until the mercury in the glass tube 29 reaches a heightof about 60 cm. inch) above the mercury in the cylinder 30. Theapparatus is supposed to be cold. Now the screw pincer 33 is closed, thesuction-pump uncoupled, and afterward the flame placed under theapparatus, which causes the mercury in the tube 29 to descend somewhat.Finally a state of equilibrium is obtained, and the temperature becomesabout 65 degrees (l. Should the temperature still be somewhat too high,then again more air is sucked out of'the apparatus, so that themercury-column rises further. If the temperature becomes however too'low, a little air is admitted to the apparatus by opening the screwpincer 32.

The final case occurs, in which it may be desired to operate attemperatures which correspond with pressures above atmospheric. For atemperature for instance of 125 degrees C, the operation proceeds asfollows:

The screw pincer 34 is closed and the pincers 31, 32 and 33 are opened.The glass tube 27 is connected, by means of a rubber tube, provided witha non-return valve (for example a bicycle tire-valve), to an air pump(for example a bicycle pump) and air is pumped intothe apparatus, untilthe mercury in the pressure gage rises to about 60 em. Now the flame isplaced underneath the apparatus, the mercury rises a little further,until the state of equilibrium is established and the gage pressurebecomes one atmosphere. Should the temperature be too low, then more airis pumped in; should it be too high, air is let out by opening thepincer 3%.

After the samples are entirely dried, the flame is removed and thesamples are allowed to cool in the apparatus itself. Here the advantageof the apparatus according to the invention comes to the front, viz.that the apparatus acts as a desiccator. Continually during the coolingas long as the apparatus is still somewhat hot, a little draft willalways remain, so that air is still drawn constantly over theconcentrated sulfuric acid.

It has been found that no danger exists of the absorption of vapor fromair, which after a cemplete cooling enters the top into the tube 1, evenafter several hours. After a couple of hours the apparatus issnfiicientiy cooled and the weighing of the samples can take place.

This weighing is done as follows In the immediate neighborhood of thetube 1 at the top, the different covers of the weighing-cups are placedone above the other in the same order as the different weighing-cups areplaced one above the other.

The framework is now hoisted until the highest weighing-cup just extendsabove the tube 1, and immediately the first cover is put on this cup.Then the framework is hoisted a little higher and the secondweighing-cup is covered and so on, proceeding rapidly until all thesamples are covered. Now the uppermost weighing-cup is removed and theframework with the other weighing-cups immediately brought down into thedrying chamber. The highest weighing-cup is now weighed. Then theframework is hoistedagain until the second cup can be removed in orderto be weighed and immediately the framework with the remaining cups isbrought down into the tube again. Every time as the framework is broughtdown air is drawn at the top into the drying-chamber and inversely acurrent of air will arise in opposite direction when hoisting theframework. In order to secure the latter, which is an advantage, becausethe air which is drawn is preliminarily dried by the sulfuric acid, sothat every time fresh dry air is brought into the drying-chamber, and toprevent air being drawn in at the top from the possibly humid laboratoryroom, :1.

non-return valve is arranged, which in the first case closes and in thesecond case remains open, as is evident from the drawing.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is 1. A drying apparatus comprising an open-endeddrying-chamber, a jacket surrounding said chamber and adapted to containwater, means for heating the water in said jacket, and means within thejacket for condensing the vapor therein.

2. A drying apparatus comprising an open-ended drying-chamber, a jacketsurrounding said chamber and adapted to contain water, means for heatingthe water in said jacket, means within the jacket for con densing thevapor therein, a frame vertically movable within the chamber, and meansfor adjustably supporting said frame within the chamber. 3. A dryingapparatus comprising a drying-chamber, a heating chamber surrounding aportion of the drying-chamber, a condensing chamber surrounding theremaining portion of the drying-chamber and communicating with theheating chamber, heating means below the heating chamber, and a pipesurrounding the heating chamber and spaced therefrom to provide achamber for the heating means.

4.. A drying apparatus comprising an open ended drying chamber, aheating chamber surrounding the drying-chamber, a. frame adjustablevertically within a dryingchamber, and trays carried by the frame, saidtrays being arranged one above the other, and alternate trays being ofan area less than the transverse area of the frame, while the remainingtrays are formed with central openings.

5. A drying apparatus comprising an open ended drying chamber, means forheating and simultaneously creating a draft through the chamber, a framemovable vertically within the drying-chamber, trays carried by theframe, and receptacles supported by certain of the trays, said traysbeing arranged to direct the draft within the drying-chamber to the topof said receptacles.

In testimony whereof I have signed my 'name to this specification in thepresence of two subscribing witnesses.

SIJTbE HERO MEIHUIZEN. Witnesses:

H. F. JoRm'rsoND,

D. L. Lnnv.

